Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Revenue	$ 3,336	$ 3,215
Expense:
Compensation and benefits	1,854	1,730
Other operating expenses	749	750
Operating expenses	2,603	2,480
Operating income	733	735
Interest income	2	3
Interest expense	(46)	(36)
Investment (loss) income	(3)	2
Income before income taxes	686	704
Income tax expense	196	206
Income from continuing operations	490	498
Discontinued operations, net of tax	0	(3)
Net income before non-controlling interests	490	495
Less: Net income attributable to non-controlling interests	9	13
Net income attributable to the Company	$ 481	$ 482
Basic net income per share
Basic net income per share - Continuing operations (usd per share)	$ 0.92	$ 0.90
Basic net income per share - Net income attributable to the Company (usd per share)	0.92	0.89
Diluted net income per share
Diluted net income per share - Continuing operations (usd per share)	0.91	0.89
Diluted net income per share - Net income attributable to the Company (usd per share)	$ 0.91	$ 0.88
Average number of shares outstanding
Average number of shares outstanding - Basic	521	539
Average number of shares outstanding - Diluted	526	545
Shares outstanding at March 31,	521	538